GRADE 11 ENGLISH MEDIUM SCIENCE KASUN MADUSHANKA

Living tissues

 A group of cells with a common origin that has been modified to perform particular
functions in the body is known as a tissue.

Plant tissues

Classification of plant tissues

 Growing part is soft and light coloured. Mature part is rough and
dark coloured. This is because of the nature of tissues.

 Plant tissues can be divided into two groups according to the

ability of cell division.
1. Meristematic tissues
2. Permanent tissues

 Permanent tissues can be found in region B-B'and Meristematic

tissues in region A-A'

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Meristematic tissues

The tissues with cells that divide actively by mitosis to produce new cells are called
meristematic tissues.

Features of meristematic tissues

 small sized living cells
 No intercellular spaces
 distinct nucleus in each cell
 Absence of large central vacuole but small vacuoles may be present
 Absence of chloroplasts
 Large number of mitochondria are present

Apical meristems
 Found in shoot apex,root apex and
axillary buds. Plant increases its height
due to apical meristems

Intercalary meristems
 Found at nodes.
 The length of internode increases due
to intercalary meristem
 They are found in plants of grass family.

Lateral meristems
 Lateral meristems are present laterally
in the
 stem and roots of plant.
 They are found parallel to the
longitudinal axis of plant.
 The diameter of the plant increases due
to the activity of this tissue.
 Cambium tissue found in dicots is a
lateral meristematic tissue.

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Permanent tissues

 A tissue that lost its ability to divide and specialized to perform a particular
function is known as a permanent tissue

Permanent tissues are two types

.
 Simple Permanent tissues - One type of cells collected together
 Complex Permanent tissues - Different types of cells collected together

Simple permanent tissues

 The tissue is composed of similar cells

 There are three types of simple permanent tissues

1. Parenchyma
2. Collenchyma
3. sclerenchyma

Parenchyma

 Forms the soft parts of the plant body

 Most abundant tissue found in the plant
Features of Parenchyma tissue
 Consists of living cells.
 Cells are spherical with a large central
vacuole.
 Nucleus is present peripherally in the
cytoplasm.
 Cell wall is thin and made up of cellulose.
 Intercellular spaces are present.

Locations of parenchyma tissues

 Cortex and pith of plant stem
 Pith and cortex of roots
 Fleshy parts of fruits
 Seeds (endosperm)
 Leaves (mesophylls)

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Functions of parenchyma

 Photosynthesis -
……………………………………………………………………………………
…………………………………………………………………………………
 Food storage -
……………………………………………………………………………………
………………………………
E.g. : Potato tuber, Carrot and Sweet potato roots,Papaw and Banana fruits.

 Storage of water - ……………………………………………………………….

E.g. : Aloe leaves, Bryophyllum leaves, Cactus cladode

 Providing support -
……………………………………………………………………………………
…………………………………………………………………….

Collenchyma

 Provides mechanical strength and support to the plant body.

Features of collenchyma tissue

 Consists of living cells.
 Cells possess a cytoplasm, nucleus and central vacuole.
 Cells are elongated and polygonal in cross section.
 corners of the cell walls are thickened.
 Intercellular spaces may present or may not present

Locations of collenchyma
 Forms a cylindrical tissue inner to the epidermis of herbaceous stems.
 Found in the veins of dicot leaves

Functions of collenchyma
 Provides mechanical support to dicot
plant stem, before the formation of
wood.
 Provides support to the plant leaves by
the collenchyma in veins.
 Photosynthesis is carried out by
Chloroplasts are found in the
collenchyma of immature dicot stems

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Sclerenchyma

 Provide mechanical strength and support to the plant body.

 This tissue has two types of cells as sclereids and sclerenchyma fibres.

Features of sclerenchyma tissue

 Consists of dead cells.
 Lignin is deposited on the cellulose cell wall.
 Cells are tightly packed. No intercellular spaces.
 Cell wall is evenly thickened and forms a central lumen

Locations of sclerenchyma tissue

 Coconut fibres, agave fibres and cotton wool are made up of sclerenchyma fibres
 Selereids are found in endocarp of coconut, Kaduru and mango fruits, the pericarp of
guava fruit and in pear fruit and seed coat of coffee and dates.

Functions of sclerenchyma
 Provide support to the plant body

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Complex permanent tissues

Xylem tissue

1. Xylem vessel elements

 Cylindrical elongated cells
 Stacked together with dissolved cross walls to form
continuous xylem vessels for water transport
2. Tracheids:
 Elongated, spindle shaped cells
 Help in water transportation
3. Fibres:
 Narrower and shorter than tracheids
 Provide support to xylem tissue
4. Parenchyma cells:
 Living cells with thin cell walls
 Involved in food storage

Functions of xylem

 Transportation of water and minerals to

the plant body which are absorbed by
plant roots.
 Providing of mechanical support to plant
body.

Phloem tissue

Phloem tissue is composed of four different

types of cells.

1. Sieve tube elements

2. Companion cells
3. Phloem fibres
4. Phloem parenchyma

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1. Sieve tube elements

 Fuse end to end with dissolved cross walls to form sieve tubes
 Cross walls called sieve plates
 Transport food (mainly sucrose) as a solution
2. Companion cells
 Elongated cells associated with sieve tubes
 Nucleus controls sieve tube activities
3. Phloem fibres:
 Dead cells scattered in phloem tissue
4. Phloem parenchyma
 Living cells

Functions of phloem tissue

 Translocate food synthesized in leaves throughout plant body

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Animal tissues

 The human body is made up of about 210 different types of cells.

Main types of animal tissues are given below.

 Epithelial tissue
 Connective tissue
 Muscle tissue
 Nervous tissue

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Epithelial tissue

What is Epithelial Tissue

 Lines internal and external surfaces of vertebrate body
 Can be single or multi-layered cells

Features
 Cell Arrangement: Tightly packed
 Basement Membrane: Cells placed on a basement membrane
 Blood Supply: Nerve supply present; no blood supply
Classification
 Cell Shape
 Number of Layers
Locations
 Blood Vessels
 Glands - Thyroid
 Cavity Linings - Nose, Bladder
 Outer Covering - Skin
Functions
 Protective Function: Lining and protection of organs
 Absorptive Function: Absorption in digestive tract
 Sensory Function: Perception of stimuli in tongue, nose
 Secretory Function: Mucus secretion in respiratory tract
 Excretory Function: Filtration in Bowman's capsule

Connective tissue

Introduction
 Composed of different types of cells and
fibers embedded in a matrix
 Possess nerve and blood supply
 Provide connection between tissues/organs
and provide support

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BLOOD TISSUE

Blood Tissue
 Special connective tissue where matrix (plasma) not secreted by cells
 Helps maintain connections between organs/tissues

Features
 Composed of fluid matrix (plasma)
 Contains cells: red blood cells, white blood cells, platelets
 Fibers not always present but appear during clotting
Functions
 Transportation (gases, nutrients, waste, hormones)
 Protection (white blood cells phagocytize and produce antibodies)
 Homeostasis

Muscle tissue

Introduction
 One of the main tissues of the human body
 Made up of muscle cells/fibers
 Cells have ability to contract and relax
 Good blood supply → receives oxygen/nutrients at high rate
 Acts as effector in coordinating responses
Types
1. Smooth Muscle Tissue
2. Skeletal Muscle Tissue
3. Cardiac Muscle Tissue

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Smooth Muscle Tissue

Smooth Muscle Tissue

 Made up of smooth muscle cells
 Found in walls of organs with cavities (digestive tract, uterus, blood
vessels, bladder)
Features
 Cells are spindle-shaped and unbranched
 Have one centrally located nucleus
 No striations
 Do not fatigue quickly
 Involuntarily controlled
Functions
 Contraction/relaxation of organ walls assists functions like digestion,
menstruation, circulation etc.
 Involuntary control allows autonomous functioning

Skeletal muscle tissue

 Made up of skeletal muscle fibers

 Associated with skeletal system
 Aid in locomotion and movement in chordates
Features
 Long, cylindrical, unbranched cells
 Multinucleate with many peripheral nuclei
 Have striations
 Many mitochondria
 Voluntarily controlled
 Fatigue easily
Examples: Biceps, triceps, leg muscles, facial muscles
Functions
 Contraction causes voluntary body movements and locomotion
 Attachment to skeleton allows posture and limb/body positions
 Fatigue prevents damage from overexertion

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Cardiac muscle tissue

 Made up of cardiac muscle cells

 Exclusively found in vertebrate hearts
Features
 Uninucleate, striated, short cells
 Intercalated discs present between cells
 Do not fatigue
 Rhythmically contract
 Involuntarily controlled
Functions

 Rhythmic contraction allows pumping of blood through circulatory system

 Involuntary control maintains heartbeat without conscious input
 Lack of fatigue allows continuous contraction

Nervous tissue

Introduction

 Important tissue found in chordates

 Structural unit is the nerve cell or neuron
 Neurons specialized to transmit nerve impulses

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Features of Neurons

 Two main parts: cell body and nerve fibers

 Cell body contains nucleus, mitochondria, Golgi body, Endoplasmic reticulum
 Axon arises from cell body, transmits impulses away
 Dendrites receive stimuli and transmit impulses to cell body
 Axons often myelinated to increase transmission speed
 Myelin sheath not continuous, gaps are nodes of Ranvier
Functions

 Receive information from receptors or other neurons

 Transmit information to effectors (muscles) or other neurons
Types of Neurons

1. Sensory Neuron
2. Inter Neuron
3. Motor Neuron

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Types of Neurons

1. Sensory Neuron
 Cell body in ganglion (collection of cell bodies)
 Dendrites in sensory organs
 Axon in central nervous system
 Transmit impulses from sensory organs to CNS
2. Motor Neuron
 Star-shaped cell body with many fibers
 One long axon (can be >1m)
 Cell body/fibers in CNS
 Transmit impulses from CNS to muscles
3. Inter Neuron
 Entire neuron in CNS
 Short axon
 Many dendrites
 Connects sensory and motor neurons

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REVISION QUESTIONS

1. What type of muscle tissue is found in the walls of organs like the digestive tract?
a) Skeletal b) Smooth c) Cardiac d) Intercalated
2. Which of these is a feature of smooth muscle tissue?
a) Striations b) Involuntary control c) Fatigue easily d) Multinucleate
Cardiac muscle tissue is located in the _____.
a) Skeleton b) Heart c) Digestive tract d) Reproductive organs
3. Which parts are present in a neuron?
a) Cell body and nerve fibers b) Node of Ranvier c) Myelin sheath d) All of the above
4. Sensory neurons transmit impulses _____.
a) From sensory organs to CNS b) From CNS to muscles c) Within CNS d) From sensory organs to muscles
5. The rhythmic contraction of cardiac muscle allows
a) Voluntary body movements b) Pumping of blood c) Fatigue resistance d) Attaching to the skeleton
6. Skeletal muscle fiber features include
a) Spindle-shaped cells b) Peripheral nuclei c) Involuntary control d) Intercalated discs
7. Which neuron type connects sensory and motor neurons?
a) Sensory b) Motor c) Interneuron d) Relay
8. Which of these is a simple plant tissue?
a) Parenchyma b) Xylem c) Sclerenchyma d) Collenchyma
9. Intercalated discs are found between
a) Skeletal muscle cells b) Smooth muscle cells c) Cardiac muscle cells d) Neurons
10. Which cells would be observed attached to a basement membrane?
a) Muscle cells b) Connective tissue cells c) Epithelial cells d) Sieve tube cells
11. Which is a characteristic feature of nervous tissue?
a) Striations b) Cell wall c) Large vacuole d) Axon
12. Dead cells are present in
a) Parenchyma b) Collenchyma c) Xylem d) Phloem

Fill in the Blanks

1. Smooth muscle tissue is found in the walls of organs like the _______ and _______.
2. _______ muscle tissue is made of long, cylindrical, unbranched cells.
3. Cardiac muscle cells possess _______ between cells.
4. The structural and functional unit of nervous tissue is the _______.
5. _______ neurons carry signals from sensory organs to the central nervous system.

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True/False Questions

1. Skeletal muscle cells are multinucleate. ……..

2. Cardiac muscle cells fatigue after prolonged activity. …….
3. Neurons contain specialized structures to allow transmission of nerve
impulses. ……..
4. Interneurons connect sensory and motor neurons in pathways. ……..
5. Smooth muscle cells have striations. ………

ESSAY QUESTIONS

A) The white blood cells, leucocytes are divided in to 2 categories depending on the availability of
granules in cytoplasm.
i) Name the leucocytes with granules and without granules.

ii) Write the function of each of the following blood corpuscles.

a) Erythrocytes
b) Leucocytes
c) Platelets

B) Muscle tissues can be divided as striated muscles, unstriated muscles and cardiac muscle.

i) Write two special features of a striated muscle.

ii) Why do striated muscles are known as voluntary muscles?

iii) Mention the places where these muscles are present in our body.

Striated muscles Unstriated muscles

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i) Name the animal tissues given below in diagrams.

ii) Write down one function performed by each of the tissue.

a) muscle tissue
b) nervous tissue
c) epithelial tissue

ii) Name another type of animal tissue, in addition to the tissues stated above.

iii) Smooth muscles are found in the human body, state 3 places smooth muscles found.

v) What common feature could be seen in a tissue when various plant and animal tissues are observed.

The classification of plant tissue is shown in the following chart.

i) Name from number i) to number viii).

ii) Mention 3 characteristics of meristemetic tissue.

……………………………………………………………………………………………..
……………………………………………………………………………………………..
……………………………………………………………………………………………..

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iii) State 2 other functions performed by the tissue, mentioned in question no (ii).
……………………………………………………………………………………………..
……………………………………………………………………………………………..
iv) State two structural different between smooth muscle fiber and skeletal muscle fiber.
……………………………………………………………………………………………..
……………………………………………………………………………………………..
v) State a characteristic which you used to identify tissue (B).
……………………………………………………………………………………………..
vi) Write 3 functions of epithelial tissue.
……………………………………………………………………………………………..
……………………………………………………………………………………………..
……………………………………………………………………………………………..

AGAIN MCQS ……. WHAT ?

1. Which of the tissue that transport water in the plant body?

1) Xylem 2) Cambium 3) Phloem 4) Pith
2. Which of the following are unbranched among the three types of muscles found in the
human body?
1) Skeletal muscle and smooth muscles only.
2) Smooth muscle and heart muscles only.
3) Skeletal muscle and heart muscles only.
4) Heart muscles, Smooth muscles and skeletal muscles.
3. The urinary bladder muscles is made of,
1) Skeletal muscles 2) Smooth muscles 3) Straited muscles 4) Branched muscles
4. In which of the following are paranchyma tissue mostly present?
1) coconut fibers 2) cotton wool 3) veins of dicot leaves 4) fleshy parts of fruits
5. Which of the following incorrectly states about the characteristics of sclerenchyma tissue?
1) Consists of dead cells.
2) Lignin is deposited on the cell wall.
3) Cells are tightly packed.
4) Intercellular spaces are present.
6. Which of the common feature for both xylem and phloem?
1) Presence of parenchyma tissue.
2) Presence of non - living tissues.
3) Both tissues produce food in the leaves.
4) Both tissues cannot provide mechanical support to plant body

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